This invention relates to a vacuum load switch with a disconnecting switch including a vacuum valve and an air disconnecting switch combined together.
In general, it is naturally required for load switches to perform the supplying or cutting-off of a load current as needed. In addition to the above, since they are housed in a switchboard or the like, the load switches are desired to permit the visual confirmation of safety, i.e. the open state of electrodes, to minimize a space to be occupied and to prevent the leakage of arcs which occur when the switch is opened or closed. It is also desired for such switch to resist the high frequent operation and have a longer life time. In some air disconnecting switches of linearly reciprocating type or blade rotating type, it is possible to perform the visual confirmation of safety and to easily obtain an insulating distance between electrodes in the open state. However, any of those disconnecting switches makes it almost impossible that arcs which occur when the switch is opened or closed are completely prevented from leaking to the outside, and the life time is prolonged while permitting the high frequent operation. On the other hand, there have been known vacuum switches as a switch of small size, which can prevent the leakage of arcs which occur when the switch is opened or closed and can resist the use of a long life time even under the high frequent operation. But the vacuum switches have such a drawback that a distance between electrodes is small in the open state. For example, the distance between electrodes is less than 10 mm in the class of 2.7 kV. Therefore, when visually judging whether the electrodes are closed or opened, there may occur erroneous judgment due to a small change in the distance between electrodes of the vacuum switch. From such condition, there has been hoped to develop a small size, long life load switch which can at least perform the visual confirmation of safety, by utilizing advantages of the air disconnecting switch and the vacuum switch while compensating disadvantages thereof.